import java.util.Scanner;

public class ToAndFro {

	public static final int MAX_MSG_LENGTH = 200;

	public static void main(String args[]) {
		Scanner in = new Scanner(System.in);

		while (true) {
			int columns = 0;
			// Enter number of columns
			if (in.hasNextInt()) {
				columns = in.nextInt();
				if (columns == 0) {
					break;
				}
			}

			// Enter encrypted message as a String and store the same character
			// by character into a char Array named "messageArr"
			if (in.hasNext()) {
				String encryptMsg = in.next();
				int messageLength = encryptMsg.length();

				// Find number of rows using columns and encrypted message
				// length
				byte rows = (byte) (messageLength / columns);

				// initialize a 2-d array for storing the encrypted message
				char[][] encryptMessageArr = new char[rows][columns];

				// store the encrypted message in 2-d array
				encryptMessageArr = storeDecryptedMessage(encryptMessageArr,
						encryptMsg);
				displayDecryptMessage(encryptMessageArr, columns);
			}
		}
	}

	// dicypher the encrypted message stored in char[], save the encrypted
	// message in 2-D array
	private static char[][] storeDecryptedMessage(char[][] encryptMessageArr,
			String messgaeArr) {
		int i = 0;
		for (int rows = 0; rows < encryptMessageArr.length; rows++) {
			int counter = 0;

			for (int col = ((rows % 2) == 0 ? 0
					: (encryptMessageArr[rows].length - 1)); counter < (encryptMessageArr[rows].length); counter++) {
				if ((rows % 2) == 0) {
					encryptMessageArr[rows][counter - col] = messgaeArr
							.charAt(i);
				} else {
					encryptMessageArr[rows][col - counter] = messgaeArr
							.charAt(i);
				}
				i++;
			}
		}
		return encryptMessageArr;
	}

	// Display the decrypted message present in 2-D array
	private static void displayDecryptMessage(char[][] encryptMsgArr,
			int columns) {
		for (int cols = 0; cols < columns; cols++) {
			for (int rows = 0; rows < encryptMsgArr.length; rows++) {
				System.out.print(encryptMsgArr[rows][cols]);
			}
		}
		System.out.println();
	}
}
